Standard enthalpy of formation is not zero for??
(A)O2(g). (B)Br2(l)
(C) Ba(g). (D)He(g)

Ch4 and ph3 are both covalent since they are composed both of non-metals.    ch4 is non- polar because of  london forces and has a geometry of tetrahedral  ph3 , on the other hand, is umbrella shaped polar and has dipole-dipole intermolecular force (imf) . since ph3 is polar, it has a stronger imf   

The correct answer is:   bri hope this answer was ! : )